Development of a Sleep Monitoring System with Wearable Vital Sensor for Home Use

This paper describes a new sleep monitoring system for home use. The basic system consists of a wearable physiological sensor and PC software for analyzing sleep quality from user’s wrist motion and heart rate variability. Different from a conventional sleep monitoring device used in a hospital, the sensor is so small and easy-to-use that a normal person can use it at home. This means that the system is useful for a sleep specialist who wants to check a patient's daily sleep pattern. The system can also be used for self-care. We have developed a wrist-watch-shaped physiological sensor that monitors user’s wrist motion and pulse wave interval. We have also developed the algorithm for computing the quality of sleep from these physiological data on PC. Although sleep is a kind of brain activity and our sensor can not directly measure it, the output of our algorithm is close to medically evaluated sleep quality. We performed dozens of comparison experiments and found that its accuracy was about 73.5% on average. The value of the accuracy is enough for assessing a normal person’s sleep quality.